The spread between London Interbank Offered Rate and the overnight index swap (Libor-OIS) — basically a measure of how expensive it is for banks to borrow — has skyrocketed over the past four months, from 0.10% to 0.58%.

Bloomberg/Credit Suisse

But the sharp widening has more to do with recent political moves than with systemic glitches in the economy, analysts at Credit Suisse wrote in a note to clients sent out on Friday.

"We believe that the widening is purely technical and is no indication of any systemic risks facing the financial sector," the analysts wrote. "Other indicators of systemic risk in the banking sector remain well behaved."

Other indexes, including the high-yield spread, aren't showing signs of stress. And there has been little significant impact on the cross-currency basis, which measures the cost of borrowing US dollars backed by foreign currencies.

After Congress voted to lift the debt ceiling last month, the US Treasury Department has been ramping up its cash balances by issuing bills. A record amount of Treasury bills and notes, about $294 billion, will likely be auctioned this week.

Additionally, the US tax overhaul passed in December incentivizes businesses to repatriate money from abroad. Because this decreases demand for offshore treasury bills, foreign banks are instead funding themselves through the interbanking market.

The current Libor-OIS spread is likely nothing more than a product of sweeping political moves over the last few months, according to analysts. But further widening could be cause for concern, especially for Americans.

A bigger gap would mean additional funding costs for more than half of US corporations, about 53%, which could hurt at a time when the Fed is also raising interest rates.

"We should see reduced upward pressure on Libor-OIS spreads by the middle of April," Credit Suisse said. "April tax receipts should ease the Treasury’s cash needs and hence reduce the need to issue bills. Moreover, the repatriation of offshore cash can be seen as a one off."